89 351 replacement options?

Hmmm. Lots of things to think about. Is there a way to visually tell if I have the big chambered heads or should I just go by part numbers? Also, maybe a silly question, but are 302 heads the same? It really wouldn't help me with parts I already have, because I think a lot of my 302s are also emissions era.

Is there a way to visually tell if I have the big chambered heads or should I just go by part numbers?

The head casting numbers will identify the head and tell you what size the chambers are.. within a couple cc's anyway, production tolerances being what they are/were you will find that each batch off the line had slightly different specs and that's why the smog era heads for example are rated as having 68-70cc chambers. It would be worth your while to pickup a set of refurbished late model heads(E7TE castings), that's what's on your '89 motor and while these aren't the greatest perfroming heads by a long shot they work well enough to make ~275hp with the right cam and are equipped with hardened seats.. something that your early heads won't have and that you'll have to spend $$ getting installed. The late model heads also have pedistal mounted rockers that don't require any setup they just bolt down with stock length pushrods.. assuming the block and heads haven't been milled down too much, and even if they are that's easily fixed with shims under the pedistal fulcrum. Bottom line is the motor will assemble easier and last longer with these heads.

I rebuilt an '85 351 years ago with zero deck pistons(with valve reliefs), stock heads that were home ported and cleaned up(chambers smoothed, exhaust ports heavily reworked), an aftermarket cam, and full length headers, and it produced about 9:1 static CR and made outstanding TQ even on regular octane fuel so I was quite pleased with it. I used a high volume oil pump but it had to be machined to fit inside the stock oilpan so I'd suggest you avoid the hastle and just use a regular volume pump, the hi-vol isn't necessary with all new bearing anyway.

I didn't realize that my 89 already has the E7TE heads. That's good to know.

That 76 engine also has pedestal rocker mounts. Maybe I'd better look for some casting numbers. The truck is a hodgepodge of parts. The title and door plate say 71, the body/grill look 72, the chassis is newer but I haven't determined a year, the carb and distributor seem to be 76 so I assumed that the entire engine was 76. When I pulled the valve cover to check for bent pushrods (with hopes that it was something simple) the valves weere tightened like a 302; 'til contact then another turn. I tightened them down tight to the pedestal and didn't really notice a difference.

Also, maybe a silly question, but are 302 heads the same? It really wouldn't help me with parts I already have, because I think a lot of my 302s are also emissions era.

LOL, not a silly question, just slightly complicated

No.........and Yes. Up to like 1977/1978 the 302 & 351 heads were different. The 351 had bigger valves and slightly bigger port dimensions than the 302 castings. There were several sizes of combustion chambers made for the 302, depending on what direction the wind was blowing when Ford made them, but most if not all were smaller than the ~60cc 351W castings. Beginning in '77/'78 the 351W and 302 were given the same head which had the small valves and large ~69cc chambers. I also seem to recall a 351W casting in the late '70s that had the larger ports of the early head but the smaller valves of the 302, but I could be wrong. The '87 E7TE truck castings were an improvement, but still not quite up to the older 351W castings. They were used on the 5.0L H.O. as well as the 5.8L truck motors. I agree that these heads (which you already have on your '89) would be fine for what you're doing and be more user friendly. I would, however, be curious to see what castings you have on the older motor....you never know what privious owners have done.

I'm not sure when the switch was made from rail rockers to fulcrum guides or the switch to hardened valve seats. There is a difference in the installed height of the valve springs between the older 351W and 302 heads and the older 351W heads also had larger head bolt holes than the 302. We used to install the older 351W heads on 289/302's for the added flow capabilities, but it required head bolt bushings, custom length pushrods and better pistons (depending on the year) to really do it right.

There were sooo many different variations on Ford small block Windsor heads that I can't remember any specifics. The best thing you can do is look at the casting numbers and measure everything to really know what you have.

Sounds to me like the late model smog heads....I think that the better older heads had positive stop studs and rail tip guided rocker arms. I would think that a '76 model would have rail rockers as well. Someone may have installed later model heads or you may have a later model engine.

Here is a chart with specs on most of the early heads. There is one questionable entry.. the very last one in the 302 section that lists an 85-87 head with a 66cc chamber and screw in studs under the F5AE casting number. I have never seen a late model production head with screw in studs and technically an F5 casting would have to be a '95 not an '85, so something is fishy here but it won't impact the OP's project so I only mention it in passing, everything else seems to be pretty accurate.

And here is a chart for the later heads. The GT40 heads are at least equal to the early 351 heads perfromance wise and have hardened valve seats of course, and the GTP heads outperform everything else listed in both charts despite slightly smaller exhaust valves(better port design), but they can cause headaches with header/manifold fitment due to a sharp sparkplug angle which is almost perpendicular to the head. There are lots of warnings about these heads on the web but generally most longtube and unequal length shorty headers fit without much problem.. maybe an odd header tube needs to be tweaked slightly that's it.